“Some common RF terms such as frequency, RF sensitivity, power gain, loss, attenuation, modulation, 3dB rule, etc. are crucial to having a better understanding of an RFID system.”
Whether you are looking to implement an RFID system, machine-to-machine (M2M) communication, IoT technology in a business setting or you simply want to expand your knowledge, knowing certain RF terms is very helpful. It also helps you decide the technical specifications of the RFID or IoT system to meet your business application requirements.
Radio Frequency (RF) technology has become an integral part of our everyday lives, from wireless communication to remote controls and RFID systems. Since RFID tag readers and antennas communicate using radio frequency signals, understanding common RF terms is crucial for anyone working with wireless technology or simply interested in the field.
This blog aims to provide a comprehensive overview of the common RF terms that are essential for a better understanding of RF technology.
RF Terms You Should Know About
1. Frequency
In simple words, Frequency is the number of occurrences of a repeating event per unit of time. In the context of RF, it refers to the number of oscillations per second of an electromagnetic wave in the radio spectrum. The frequency in an RFID system is measured in Hertz (Hz), where 1 Hz equals one cycle per second. The higher the frequency of an RF signal, the lower the wavelength.
Common frequency bands in RFID include UHF (Ultra High Frequency, 860-960 MHz), HF (High Frequency, 13.56 MHz), and LF (Low Frequency, 125 kHz and 134 kHz).
While selecting an RFID system, the choice of RFID frequency also depends upon the RFID application requirements in a business setting. For applications such as Warehouse asset tracking and inventory control, retail asset tracking and POS operations, and manufacturing and supply chain operations, UHF (Ultra High Frequency) with long read range is the most suitable.
For applications such as access control, digital payment, hotel key card access, identification, and tracking, the HF/NFC (13.56 MHz) frequency RFID system is most frequently used. HF RFID/NFC systems offer a read range of a few inches.
2. Bandwidth
Bandwidth refers to the range of frequencies within a band that can be used for transmitting signals. It is the difference between the upper and lower frequencies in a continuous band of frequencies. For example, a bandwidth of 20 MHz means that the signal can contain frequencies from 100 MHz to 120 MHz.
3. RF sensitivity
In an RFID system, RF sensitivity or receiver sensitivity of an RFID reader or antenna refers to the minimum signal strength that a receiver can detect. It is denoted in dBm (negatively). For an efficient RFID system, RF sensitivity should be around -80dBm to -100 dBm. For an IoT system, having a receive sensitivity of -140dBm is preferred.
4. Modulation
Modulation is the process of varying one or more properties of a high-frequency periodic waveform, called the carrier signal, with a modulating signal that contains information to be transmitted. Common types of modulation include Amplitude Modulation (AM), Frequency Modulation (FM), and Phase Modulation (PM).
5. Antenna
In RFID technology, antennas are crucial for the transmission and reception of signals. RFID antennas are used with RFID tags and RFID readers to transmit and receive RF signals at the RFID tag and reader end respectively.
There are various types of antennas, such as dipole, Yagi, parabolic, and patch antennas, each with specific use cases and characteristics. In an RFID system, the antenna power gain, read range, and polarization of the antenna play a crucial role.
6. Gain
The gain of an antenna, or antenna power gain, is a measure of the efficiency of the antenna in transmitting or receiving electromagnetic waves. It is usually measured in decibels (dB) and indicates how much power is transmitted in the direction of the signal compared to an isotropic radiator (a theoretical point source that radiates equally in all directions).
7. dB (Decibel)
Decibel is a unit used to express the ratio of two values of a physical quantity, often power or intensity. In RF, it is commonly used to measure the gain or loss in power of a signal. For example, a signal with a gain of 3 dB means that its power is doubled and a loss of 3dB means the signal power is lost 50% (halved).
8. 3dB Rule
In an RF system, the 3dB rule refers to how we calculate antenna gain or loss. Since decibel (dB) is a logarithmic scale on which the gain ratio is expressed, a gain ratio (Out/In) of 8 would be 9dB, as 10*log (8)=9.
A 3 dB gain means twice the power as the gain ratio of 2 is equal to 3dB, since 10*log(2)=3. Similarly, a 3 dB loss means half the power. For example, a system with 60 watts of input power having a 6 dB insertion loss will mean that the output power is only 15 watts as every 3db gain loss will mean that power is getting halved.
9. dBm
It provides an absolute measurement of power relative to 1 milliwatt. The m in dBm refers to the milliwatt. So, 0 dBm will mean 1.0 milliwatt, 10 dBm equals 10 milliwatt and 30 dBm equals (1 mW x 1,000) equals 1 watt.
10. RF Attenuation
In an RF system, attenuation can be caused by factors such as distance, obstacles, and interference, leading to a decrease in the strength of the signal, either the amplitude or the intensity. While designing an RFID antenna, attenuation plays an important role in ensuring efficient read range. Keeping that in mind, the appropriate RF sensitivity is important in an RFID system, in capturing the RF signals efficiently.
11. Duplex
Duplex refers to the ability of a communication system to transmit and receive signals simultaneously. In RF, duplex communication can be achieved through methods such as Frequency Division Duplex (FDD) and Time Division Duplex (TDD).
To conclude, having a proper understanding of common RF terms is essential for anyone involved in wireless communication, RF engineering, or related fields. As the field of RF technology is vast and constantly evolving, it is better to understand these RF terms like frequency, gain, loss, RF sensitivity, attenuation, modulation, etc. because only then you can decide on the best RFID, M2M, and IoT solution for your business application.
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